Conventionally, there is provided a device for converting light from linearly polarized light to circularly polarized light. For example, a simple structure such as a transmission type polarizing plate or polarizing film is used for converting visible light or infrared light into circularly polarized light. Moreover, there is also provided an undulator for spirally meandering an electron beam to carry out a conversion into circularly polarized light by periodically applying a magnetic field in a horizontal or perpendicular direction with respect to an orbit of the electron beam (for example, see Patent Documents 1 and 2).    Patent Document 1: Japanese Laid-Open Patent Publication No. 7-288200    Patent Document 2: Japanese Laid-Open Patent Publication No. 9-219564
An X-ray is included as a kind of light. The X-ray is an electromagnetic wave having a wavelength of approximately 1 [pm] to several tens [nm] which includes a hard X-ray and a soft X-ray. The hard X-ray is an X-ray having a high energy and a great transmission to a substance and is used for taking an X-ray photograph, for example. On the other hand, the soft X-ray is an X-ray having a lower energy than the hard X-ray, a high absorption into a substance and a small transmission. The soft X-ray converted into circularly polarized light is regarded to be easily absorbed into a substance because of a small transmission and to enable a detection of an electronic spin state in the substance, and therefore, is expected as effective means for an intravital test or a genetic analysis.